Much effort has been expended in developing alternate heating sources due to the ever escalating costs of energy and availability of fuel or electricity for heating purposes. Many different forms of wood stoves, for example, have been developed in recent years as alternate heat sources. But, wood fired heaters have yet been able to attain any consistent degree of thermal efficiency. Furthermore, control of temperature is difficult in such heaters as such control is dependent upon the nature of the fuel being burned and many other conditions that are not easily controlled.
A partial solution has been found in the development of pelletized fuel. Organic "bio-mass" materials are processed and formed into small solid pellets. These can be fed by mechanical means at a metered rate into a burner. Control of the feed rate has proven to facilitate greater control of the burning temperatures. Increased efficiency has also been attainable. However, there has still remained much room for improved performance.
Control of combustion air through a burner has long been a troublesome area. This is due at least in part to dependence upon convection air currents and pressure differential between the building interior and outside ambient air. Wind, for example, can have a substantial affect on the amount of combustion air being drawn into a stove or burner from within an associated building. The lack of ability to precisely control the amount of combustion air entering a burner has hampered efforts to achieve greater burning efficiency, even with modern forms of burners using pelletized fuel.
It has therefore become increasingly desirable to obtain some form of heater that will operate efficiently and effectively to completely burn the fuel within. This is desirable not only to obtain the maximum thermal value from the material being burned, but also to reduce the amount of pollutants exhausted from the burner.